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Isolement, caractérisation et cibles de nouveaux Inhibiteurs de protéases pour la création de plantes transgéniques résistantes aux pucerons

Abstract : Among the phytophagous insects, aphids show the particularity of feeding on sap. Their stylets allow them to reach the phloem tissues, a compartment which protein/amino acid ration is low. In this context, aphids are considered to be devoid of the enzymatic stock capable of hydrolysing protein. Strategies using proteinase inhibitor (PI) as entomotoxic polypeptide are considered at first inadequate to fight this kind of insects. Nevertheless, several PI have paradox toxicity against aphids.
This study is aimed at increasing the number of potential novel PI, at understanding their function in order to introduce them in biologic fight program.
During this work, new informations on digestive proteolysis in Homoptera were gained: cystein proteinase cathepsins (lysosomal enzyme) are specifically expressed in gut and in a specialized organ, the bacteriocyte. They are potential targets of cystein-PI. Seedrapes expressing Oryzacystatine (isolated from rice seed) induce a 25% reduction of Myzus persicea fecundity. This result shows the possibility to express PI in phloem to fight aphids.
Improvement of a serine-PI (isolated from pea) via directed mutagenesis was performed but no active form was obtained neither in Pichia pastoris nor in Arabidosis thaliana expression system.
We tried to enlarge the gene pool to fight aphids. Isolation of a new cystein-PI from aphid haemolymph was initiated at the molecular and biochemical level. These results show that PI constitute a new strategy to fight aphids.
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Contributor : Céline Deraison <>
Submitted on : Wednesday, August 4, 2004 - 5:08:31 PM
Last modification on : Wednesday, February 24, 2021 - 11:26:07 AM
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  • HAL Id : tel-00006629, version 1
  • PRODINRA : 251853

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Céline Deraison. Isolement, caractérisation et cibles de nouveaux Inhibiteurs de protéases pour la création de plantes transgéniques résistantes aux pucerons. Biochimie [q-bio.BM]. Université Paris Sud - Paris XI, 2002. Français. ⟨tel-00006629⟩

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